KR100335090B1 - Shadow mask in color braun tube - Google Patents

Abstract

The present invention relates to a shadow mask of a color CRT which can prevent wrinkles, and the present invention relates to an effective surface portion having a plurality of slots through which an electron beam passes, and a frame extending from the effective surface portion and coupled to a panel of the CRT. A shadow mask for a color CRT including an edge portion welded to the shadow mask, wherein the distance between the welding points of the edge portions is determined according to the thickness of the shadow mask or the pitch of the slots of the shadow mask.

Description

Shadow mask {SHADOW MASK IN COLOR BRAUN TUBE} of color CRT

The present invention relates to a color CRT, and more particularly, to a structure of a shadow mask of a CRT that can effectively prevent wrinkles occurring after welding.

The structure of a general color CRT will be described with reference to FIGS. 1 and 2.

The color CRT consists of a panel (1) coated with a fluorescent film (9) on the inner side and a funnel (3) coated with graphite having conductivity on the inner side, and the panel (1) and the funnel (3) are fused glass. Are combined with each other. An end of the funnel 3 is equipped with an electron gun 5 for generating an electron beam, and a neck of the funnel 3 is equipped with a deflection yoke 7 for deflecting the electron beam.

On the other hand, the shadow mask 30 that serves to select the color to emit the fluorescent film 9 applied to the inner surface of the panel 1 is coupled to the frame 13, the frame 13 is a spring 17 It is to be coupled to the stud pin 19 of the panel (1) using. In addition, an inner shield 21, which is a magnetic shield body that prevents the electron beam from escaping from the original trajectory under the influence of the external geomagnetism, is mounted to the rear of the frame 13.

On the other hand, since the inside of the color CRT is a high vacuum, there is a fear that the expansion is caused by an external impact. Therefore, to prevent this phenomenon, the panel 1 is designed to have a structural strength that can withstand atmospheric pressure. Moreover, by attaching the reinforcing band 23 to the skirt of the panel 1, the stress which a CRT tube of a high vacuum state receives is disperse | distributed and the impact resistance performance is improved.

Referring to Figures 3 to 6, the shadow mask and frame coupling structure will be described in detail as follows.

The shadow mask 30 has an effective surface portion 32 and an effective surface portion 32 in which many electron beam passing holes, that is, slots 38, are formed to allow electron beams from the electron gun 5 to pass through to emit the fluorescent film 9. It consists of an edge 34 which is not formed with a slot 38 to reinforce the strength of 32. The shadow portion 30 is coupled to the frame 13 by welding the edge portion 34 to the frame 13 by welding.

Meanwhile, the above-described shadow mask 30 is designed to prevent the shadow mask 30 from shaking, that is, howling. That is, howling is prevented by increasing the natural frequency of the shadow mask 30 by applying tension in the vertical direction of the shadow mask 30 (when viewed from the front of the brown tube).

It will be described in detail as follows. First, as shown in FIG. 3, the compression load P is first applied to the frame 13 having appropriate rigidity. Next, as shown in FIG. 4, after the shadow mask 30 is placed on the frame 13 in the state in which the compression load P is applied to the frame 13, the frame is subjected to resistance welding using the welding roller 40. Remove the compressive load applied to (13). Then, the frame 13 is restored to its original position by the elastic force, and thus the shadow mask 30 is in a state where tension is applied.

Referring to the operation of the color CRT configured as described above is as follows.

When an image signal is input to the electron gun 5, hot electrons are emitted from the electron gun 5, and the emitted electrons proceed toward the panel 1 while undergoing an acceleration and focusing process by the acceleration electrode and the focusing electrode of the electron gun 5. . At this time, the path of the electron beam is adjusted by the deflection yoke 7 and scanned on the inner surface of the panel 1. The electron beam scanned in the panel direction passes through the slots 38 of the shadow mask 30, and color selection is performed. The selected electron beam collides with the fluorescent film 9 formed on the inner surface of the panel 1, and the fluorescent film 9 By emitting light, the video signal is reproduced.

On the other hand, in recent years, high precision and light weight of the CRT are required. For this purpose, it is conceivable to reduce the pitch Ph of the shadow mask 30 or to make the thickness t thin so that the CRT can be made highly accurate and light.

However, simply reducing the pitch Ph or decreasing the thickness t of the shadow mask 30 has another problem, that is, it is difficult to avoid wrinkles caused by deformation of the shadow mask 30 after welding. This is because the stress concentration around the welding point 36 varies depending on the thickness t and the horizontal pitch Ph of the shadow mask 30. That is, as shown in FIG. 6, when the compressive force P is removed after welding the shadow mask 30, tension is applied to the shadow mask 30, and stress is concentrated around the welding point 36. That is, the stress generated near the welding point 36 is larger than the average stress σn, and the stress near the welding point becomes larger (σ3> σ2> σ1) and the maximum stress exceeds the yield stress. Wrinkles occur.

Therefore, in order to realize high precision and light weight of the CRT through subdividing and thinning the pitch of the shadow mask, an appropriate solution for preventing stress concentration above a certain limit is required.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a shadow mask of a color CRT that can effectively prevent wrinkles occurring after welding while realizing thinning of the shadow mask and subdividing of the pitch.

1 is a side view showing a cut part of a typical color CRT

Figure 2 is a cross-sectional view showing a coupling structure of the shadow mask of a common color CRT

3 is a perspective view of the frame of FIG.

4 is a perspective view schematically showing a welding process of a shadow mask of a general color CRT

5 is a plan view schematically showing a welding spot when welding a shadow mask;

6 is a stress state diagram showing the stress concentration phenomenon occurring in the shadow mask

7 is a graph showing the stress concentration coefficient according to the pitch, thickness, and spacing between welding points of the slots of the shadow mask;

Explanation of symbols for main parts of the drawings

1 panel 3 funnel

13: frame 30: shadow mask

38: slot 36 of the shadow mask: welding point

40: welding roller Ph: pitch of slot

L: Spacing between welding points t: Thickness of shadow mask

In order to achieve the above object, the present invention is a shadow for a color CRT tube including an effective surface portion formed with a plurality of slots through which the electron beam passes, and an edge portion formed extending from the effective surface portion and welded to a frame coupled to the panel of the CRT. In the mask, the interval of the welding point of the edge portion provides a shadow mask, characterized in that determined according to the thickness of the shadow mask or the pitch of the slot of the shadow mask.

Here, the spacing of the welding point is preferably between 11-19 times the thickness of the shadow mask. In addition, the spacing of the welding point is preferably between 0.5-1.9 times the slot pitch of the shadow mask.

Therefore, according to the present invention, it is possible to set the optimum welding point spacing where wrinkles do not occur regardless of the thickness and pitch of the shadow mask. As a result, it is possible to effectively prevent defects of shadow masks due to wrinkles, thereby improving productivity, and also reducing costs due to defects.

Hereinafter, with reference to the accompanying drawings, a shadow mask of a color CRT according to the present invention will be described.

In the present invention, the structure of a shadow mask, a frame to which the shadow mask is coupled is the same as in the prior art. However, the stress concentration around the welding point is minimized by appropriately adjusting the spacing of the welding point of the shadow mask according to the thickness of the shadow mask and the pitch of the slot.

5 and 6, the shadow mask according to the present invention will be described in detail.

The maximum stress due to stress concentration can generally be expressed by the following equation.

σ (max) = Kt * σn

Here, sigma (max) is the maximum stress generated in the stress concentration portion, Kt is the stress concentration coefficient, sigma n means the average stress.

As can be seen from the above equation, the larger the stress concentration coefficient, the greater the maximum stress in proportion to it.

The maximum stress generated around the welding point of the shadow mask can also be expressed by the above equation. If the maximum stress around the welding point in the shadow mask exceeds the yield stress, wrinkles are caused by plastic deformation. Therefore, if the stress concentration coefficient is made small, the maximum stress can be made small, and wrinkles can be prevented from occurring around the welding point.

However, it is known that the maximum stress or stress concentration coefficient is related to the shape of the cross section and the type of load, but it is virtually impossible to calculate it by the mechanical method. Accordingly, the inventors have found that through many efforts, such as computer simulations and experiments, the stress concentration coefficient generated around the welding point is related to the following factors.

Kt = f (t, Ph, L)

Where t is the thickness of the shadow mask, Ph is the horizontal pitch of the slot, and L is the spacing between the welding points.

That is, as shown in Figure 7, the stress concentration coefficient is a function of the thickness (t) of the shadow mask, the horizontal pitch (Ph) and the spacing (L) between the welding point, the stress concentration is controlled when appropriately adjusted We confirmed that we could find the range that would be minimized.

In addition, the factors that can minimize the above-mentioned stress concentration are the thickness (t), the horizontal pitch (Ph) and the spacing (L) of the welding point of the shadow mask, so that even if the thickness (t) and the pitch (Ph) are appropriately welded Adjusting the distance (L) between the points means that the occurrence of wrinkles can be prevented.

In the computer simulation, the influence of the shadow mask thickness (t) and the welding distance (L) on the crease was investigated. The interval L of the welding spot was set to a multiple of the thickness t of the shadow mask, that is, 5 to 23 times to determine whether wrinkles occurred in each case. As a result, when the space | interval L of a welding spot was in the range of about 11 times to 19 times the thickness t of a shadow mask, wrinkles did not generate | occur | produce, and it confirmed that wrinkles generate | occur | produced in the other range.

Next, in the computer simulation, the effect of the slot pitch (Ph) of the shadow mask and the spacing (L) of the welding point on the wrinkle generation was investigated. For this purpose, the simulation shows that the distance L between the welding spots is 0.3 times to 2.1 times the pitch Ph, and the distance L between the welding spots is 1.9 to approximately 0.5 times the horizontal pitch Ph of the shadow mask. Wrinkles did not occur in the range of the pear.

Such computer simulations were confirmed by direct experiment. As a result, when the shadow mask has a thickness (t) of 0.08-0.1 mm and the slot pitch (Ph) is 0.8 mm, the most stable welding point spacing (L) that does not cause wrinkles around the weld point is 1.1-1.2. mm. The spacing L of the welding spot corresponds to about 11-15 times the shadow mask thickness t, and corresponds to 1.3-1.5 times the slot pitch Ph. That is, even by experiments, it was confirmed that when the interval L of the welding point was set by the method proposed in the present invention, wrinkles did not occur around the welding point.

Referring to the effect of the shadow mask of the color CRT according to the present invention as follows.

First, according to the present invention, it is possible to set an optimal welding point spacing where wrinkles do not occur regardless of the thickness and pitch of the shadow mask. Therefore, since the defect of the shadow mask due to wrinkles can be effectively prevented, the productivity can be improved, and the cost can be reduced due to the defect reduction.

Second, even if the thickness of the shadow mask becomes thinner or the pitch becomes small, it is possible to prevent the occurrence of wrinkles occurring after welding by determining the interval of the welding point that is suitable for this. Therefore, since the shadow mask can be thinned and subdivided, there is an advantage that the high precision and light weight of the CRT can be achieved.

Claims (5)

In the shadow mask for a color CRT tube comprising an effective surface portion formed with a plurality of slots through which the electron beam passes, and an edge portion extending from the effective surface portion and welded to a frame coupled to the panel of the CRT. The distance between the welding point of the edge portion is a shadow mask, characterized in that determined according to the thickness of the shadow mask or the pitch of the slot of the shadow mask. The shadow mask of claim 1, wherein the spacing of the welding spots is between 11-19 times the thickness of the shadow mask. 3. The shadowmask of claim 2 wherein the spacing of the weld points is between 11-15 times the thickness of the shadowmask. The shadow mask of claim 1, wherein the spacing of the welding points is between 0.5-1.9 times the slot pitch of the shadow mask. 5. The shadowmask of claim 4, wherein the spacing of the weld points is between 1.3-1.5 times the slot pitch of the shadowmask.